Joanne Moncrieff of University College London ‘disproves link between low serotonin and depression

Antidepressants do work, insist top doctors as they hit back at bombshell study 

Top psychiatrists have rounded on the authors of a bombshell study which cast doubts on the effectiveness of antidepressants, labelling the findings ‘absurd’ and ‘grossly exaggerated.’

Last week, researchers at University College London said they had disproved a theory dating back to the 1960s that depression is caused by low levels of serotonin, a chemical in the brain believed to control mood.

Led by Professor Joanna Moncrieff, a respected consultant psychiatrist, the study analysed decades of research, involving tens of thousands of patients with the condition, and found ‘no convincing evidence’ of a link between the mental illness and serotonin levels.

Professor Joanna Moncrieff, pictured, a consultant psychiatrist at University College London, has led a team of researchers who have disproved the long-held believe of a link between low serotonin levels and depression 

The findings have been deemed significant as most antidepressants – taken by more than eight million Britons – are designed to boost serotonin levels.

‘Thousands suffer from side effects of antidepressants, including the severe withdrawal effects that can occur when trying to stop them, yet prescription rates continue to rise,’ Prof Moncrieff said. ‘We believe this has been driven by the false belief that depression is due to a chemical imbalance. It is time to inform the public this belief is not grounded in science.’

However, leading brain experts have criticised Prof Moncrieff, who has written bestselling books that cast antidepressants in a negative light. They argue it is untrue to say scientists believe depression is caused by low serotonin levels. Instead, they say, the prevailing theory is depression is caused by many factors, and that antidepressants are clinically shown to help.

Dr Michael Bloomfield, consultant psychiatrist and a colleague of Prof Moncrieff’s at University College London, said her conclusion ‘does not make sense’.

‘Depression has many different symptoms and I don’t think I’ve met any serious scientists or psychiatrists who think that all causes of depression are due to a simple chemical imbalance in serotonin.’

He added: ‘[This paper] has lumped together depression as if it is a single disorder, which from a biological perspective does not make any sense.’

David Curtis, Honorary Professor, UCL Genetics Institute, agreed: ‘The notion of depression being due to a chemical imbalance is outmoded, and the Royal College of Psychiatrists wrote this was an over-simplification in a statement published in 2019.’ Phil Cowen, Prof of Psychopharmacology at the University of Oxford, appeared to accuse Prof Moncrieff of cherry-picking data to suit her hypothesis.

Medics in the 1960s first found a link between low serotonin levels and depression, later providing GPs with a weapon to target the condition

Medics in the 1960s first found a link between low serotonin levels and depression, later providing GPs with a weapon to target the condition

He pointed out the review had omitted a pivotal study that did suggest depressed patients had lower levels of compounds integral to serotonin production in their blood.

‘The possible role of serotonin in depression is a separate question from the antidepressant effects of [antidepressants],’ he said.

Other experts point to multiple studies that show taking antidepressants can lift depression, regardless of their effect on serotonin levels.

‘Through years of research we know that antidepressants work and save lives,’ says Professor David Nutt, head of the Centre for Neuropsychopharmacology at Imperial College London.

‘This paper’s conclusions are absurd. The authors have grossly exaggerated the importance of serotonin levels. No one has ever said a serotonin imbalance is the sole cause of depression.’

He adds that newer studies, not included in Prof Moncrieff’s review, that used more accurate testing methods, had found ‘decreased serotonin release capacity’ in people with depression. ‘To dismiss the serotonin hypothesis of depression at this point is premature,’ he said.

Psychiatrists say the exact reason antidepressants work is not understood, but this is not unusual. ‘It’s hard to be absolutely sure what is causing a drug to work in the brain,’ says Prof Nutt. ‘In the case of antidepressants, it could be having an effect on other things than serotonin receptors.’

Crucially, they argue that, even if depression is not caused by a serotonin imbalance, this doesn’t mean it cannot be effectively treated by boosting levels of the brain chemical.

Responding to the criticism, Prof Moncrieff said the aim of the study was not to argue that antidepressants don’t work but to question whether the pills should be prescribed in the first place.

‘People are told the reason they feel depressed is that there is something wrong with the chemistry in their brain and antidepressants could put it right. But if there’s no evidence there’s anything wrong with the brain’s chemistry, then that doesn’t sound like a sensible solution. This profession has misled people for so long about the need for antidepressants and now doctors don’t want to admit they got it wrong.’